The present invention relates to a manufacturing method for white light source, especially to a manufacturing method for high-brightness white light source by an ultraviolet light source and suitable phosphors directly or indirectly excited by the ultraviolet light source.
A white light source is generally provided by mixing light source of different wavelength and the white light sensed by human vision is generally composed of light of at least two colors. For example, a conventional white light source can be realized by mixing red light, green light and blue light with suitable intensity ratio. Alternatively, the white light source can be realized by mixing yellow light and blue light with suitable intensity ratio.
The conventional white light source generally uses at least phosphors of different color to ensure color-rendering property. However, one of the prerequisites to provide high-efficiency white light source is that light from the exciting light source can be absorbed by all the phosphors. Moreover, all the phosphors have compatible absorption coefficients with respect to the light from the exciting light source. Furthermore, the quantum efficiencies of the phosphors should be compatible to facilitate light mixing.
As can be seen above description, the phosphors should be prudently chosen to have absorption band matched with the wavelength of the exciting radiation. Moreover, the phosphors should have compatible absorption coefficients and quantum efficiency to provide white light of high quality. Those requirements place a strict constrain to the materials of the phosphors.
It is the object of the present invention to provide a manufacturing method for high-brightness white light source by ultraviolet light source and suitable phosphors, wherein one phosphor is excited by the ultraviolet light source and other phosphors are excited by the light re-emitted from the phosphor excited by the ultraviolet light.
In one aspect of the present invention, the present invention provides a manufacturing method for white light source utilizing an ultraviolet light source and suitable phosphors. One of the phosphors is excited by the ultraviolet light source and generates a radiation with longer wavelength. Other phosphors are excited by the radiation with longer wavelength and generate radiation with much longer wavelength. The lights generated by those phosphors are mixed to form a white light.
In another aspect of the present invention, the present invention provides a manufacturing method for white light source utilizing an ultraviolet light source and suitable phosphors. The phosphors are directly and indirectly excited by the ultraviolet light source and the lights generated by those phosphors are mixed to form a white light. Therefore, the ultraviolet light source and the phosphors are packaged to form a white light source with low operation current.
The various objects and advantages of the present invention will be more readily understood from the following detailed description when read in conjunction with the appended drawing, in which: